The present invention relates to a new and distinctive barley cultivar designated Pronghorn. All publications cited in this application are herein incorporated by reference.
Barley (Hordeum vulgare L.) is a grain that is grown worldwide with three main market classes, malt, feed and food. Most of the barley grain produced in the United States is used as an ingredient in cattle, pig, or poultry feed. Another major use for barley is malt production. Malt is used in the brewing and distilling industries to produce alcoholic beverages. Barley varieties that are preferred for producing malt are selected on the basis of characteristics such as kernel plumpness, low protein content and low Beta-glucan content. Barley grain that has more than about 13.5 wt. % protein on a dry basis or is too dark in color is rejected by malting plants. Significant overlap between the classes can occur since barley that does not meet malting specifications can be used for feed, food and potentially the emerging biofuels industry.
Barley is a nutritious food ingredient for humans or household pets. When used as a food ingredient, malting or feed barley grain that has a cemented hull (referred to as covered) must be processed to remove that hull. A commonly used processing step known as pearling removes the hull and a substantial portion of the bran and the germ to produce a pearled barley grain, such that at least about 15 to about 40 wt. % of the outer grain is removed. Barley varieties developed especially for food are hulless, i.e., they have a loose hull so do not have to be pearled prior to consumption. Hulless barley must be cleaned as do all grains prior to entering the human food markets, but loose hulls can be removed easily with only slight modifications to the cleaning plants. Food ingredient manufacturers may grind the cleaned barley to produce flour or roll the barley to produce flakes. Food ingredient manufacturers may also utilize the cleaned barley as a whole berry (seed).
Waxy barley is a naturally occurring variant that has recently been investigated for potential in food and industrial processing. Barley lines having the waxy phenotype have reduced amounts of amylose starch in the seed. The waxy trait may be useful in the production of high maltose syrup from barley (U.S. Pat. No. 4,116,770, Goering 1978) and in the production of flour and flakes (U.S. Pat. No. 5,614,242, Fox 1997 and U.S. Pat. No. 6,238,719, Fox, 2001) that have health benefits.
The health promoting benefits of barley consumption have been investigated in human clinical trials. Studies have shown that individuals consuming barley that contains Beta-glucan soluble fiber have significant reductions in total and LDL plasma cholesterol (Behall et al. 2004. Am. J. Clin. Nutr. 80:1185-1193; Behall et al. 2004. J. Amer. Coll. Nutr. 23:55-62) as well as blood pressure (Hallfrisch et al. 2003. Cer. Chem. 80:80-83; Behall et al. 2006. Nutrition. Res. 26:644-650). In May 2006, the FDA granted a petition to allow foods containing barley with 0.75 g of Beta-glucan to carry a health claim “barley lowers cholesterol when consumed as part of a healthy diet” (Federal Register 71(98):29248-29250).
Cultivated barley is a naturally self-fertilizing species, although there is a small percentage of cross-fertilization. Natural genetic and cytoplasmic male sterility is available to use in breeding and in hybrid seed production. Using all of the tools available to a breeder, it is possible to develop pure lines that are uniform in growth habit, maturity, yield, and other qualitative and quantitative characteristics. These lines can be released as inbred varieties, as inbreds for hybrid barley, or as lines to be further manipulated in the development of new lines or varieties or that incorporate proprietary genetic material.
Barley varieties may differ from each other in one or more traits and can be classified and differentiated according to the specific traits they possess. For example, there are types of barley known as two-rowed and other types known as six-rowed, referring to the number and positioning of kernels on the spike. Barley lines also can be classified as spring barley or winter barley, referring to the growth habit, or by the adherence of hulls on the seed, or by the type of starch in the seed. There are, of course, many other traits which differentiate the various lines. A discussion of breeding methods for developing barley lines and of some traits in barley can be found in Foster, A. E., Barley, pp. 83-125, and in Fehr, W. R., ed., Principles of Cultivar Development Vol. 2 Crop species. Macmillan, New York (1987). Once a breeder has developed a pure line, it may be given a unique name and released as a cultivar under that name. While named cultivars are not necessarily pure lines (they could be a mixture of genotypes or even be a hybrid) presently, most named barley cultivars are pure lines.
The present invention relates to a new and distinctive barley variety, designated Pronghorn, which has been the result of years of careful breeding and selection as part of a barley breeding program. There are numerous steps in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals. The goal is to combine in a single variety an improved combination of desirable traits from the parental germplasm. These important traits may include higher seed yield, resistance to diseases and insects, tolerance to drought and heat, better agronomic qualities and improved grain quality.
Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is sib-pollinated when individuals within the same family or line are used for pollination. A plant is cross-pollinated if the pollen comes from a flower on a different plant from a different family or line. The term cross-pollination herein does not include self-pollination or sib-pollination.
A cross between two different homozygous lines produces a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two heterozygous plants each that differ at a number of gene loci will produce a population of plants that differ genetically and will not be uniform. Regardless of parentage, plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. The term “homozygous plant” is hereby defined as a plant with homozygous genes at 95% or more of its loci. The term “inbred” as used herein refers to a homozygous plant or a collection of homozygous plants.
Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of variety used commercially (e.g., F1 hybrid variety, pureline variety, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, and recurrent selection.
The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination and the number of hybrid offspring from each successful cross.
Pedigree breeding is commonly used for the improvement of self-pollinating crops. Two parents that possess favorable, complementary traits are crossed to produce an F1. An F2 population is produced by selfing or sibbing one or several F1s. Selection of the best individuals may begin in the F2 population; then, beginning in the F3, the best individuals in the best families are selected. Replicated testing of families can begin in the F4 generation to improve the effectiveness of selection for traits with low heritability. At an advanced stage of inbreeding (i.e., F5, F6 and F7), the best lines or mixtures of phenotypically similar lines are tested for potential release as new varieties.
Backcross breeding has been used to transfer genes for simply inherited, qualitative, traits from a donor parent into a desirable homozygous variety that is utilized as the recurrent parent. The source of the traits to be transferred is called the donor parent. After the initial cross, individuals possessing the desired trait or traits of the donor parent are selected and then repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., variety) plus the desirable trait or traits transferred from the donor parent. This approach has been used extensively for breeding disease resistant varieties.
Each barley breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful varieties produced per unit of input (e.g., per year, per dollar expended, etc.).
Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination and the number of hybrid offspring from each successful cross. Recurrent selection can be used to improve populations of either self- or cross-pollinated crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued. Plants from the populations can be selected and selfed to create new varieties.
Another breeding method is single-seed descent. This procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one-seed sample to plant the next generation. When the population has been advanced from the F2 to the desired level of inbreeding, the plants from which lines are derived will each trace to different F2 individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F2 plants originally sampled in the population will be represented by a progeny when generation advance is completed. In a multiple-seed procedure, barley breeders commonly harvest one or more spikes (heads) from each plant in a population and thresh them together to form a bulk. Part of the bulk is used to plant the next generation and part is put in reserve. The procedure has been referred to as modified single-seed descent. The multiple-seed procedure has been used to save labor at harvest. It is considerably faster to thresh spikes with a machine than to remove one seed from each by hand for the single-seed procedure. The multiple-seed procedure also makes it possible to plant the same number of seeds of a population each generation of inbreeding. Enough seeds are harvested to make up for those plants that did not germinate or produce seed.
Bulk breeding can also be used. In the bulk breeding method an F2 population is grown. The seed from the populations is harvested in bulk and a sample of the seed is used to make a planting the next season. This cycle can be repeated several times. In general when individual plants are expected to have a high degree of homozygosity, individual plants are selected, tested, and increased for possible use as a variety.
Molecular markers including techniques such as Starch Gel Electrophoresis, Isozyme Eletrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs), and Single Nucleotide Polymorphisms (SNPs) may be used in plant breeding methods. One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers, which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome.
Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select for the genome of the recurrent parent and against the markers of the donor parent. Using this procedure can minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program (Openshaw et al. Marker-assisted Selection in Backcross Breeding. In: Proceedings Symposium of the Analysis of Molecular Marker Data, 5-6 Aug. 1994, pp. 41-43. Crop Science Society of America, Corvallis, Oreg.). The use of molecular markers in the selection process is often called Genetic Marker Enhanced Selection.
The production of double haploids can also be used for the development of homozygous lines in the breeding program. Double haploids are produced by the doubling of a set of chromosomes (1N) from a heterozygous plant to produce a completely homozygous individual. This can be advantageous because the process omits the generations of selfing needed to obtain a homozygous plant from a heterozygous source. Various methodologies of making double haploid plants in barley have been developed (Laurie, D. A. and S. Reymondie, Plant Breeding, 1991, v. 106:182-189. Singh, N. et al., Cereal Research Communications, 2001, v. 29:289-296; Redha, A. et al., Plant Cell Tissue and Organ Culture, 2000, v. 63:167-172; U.S. Pat. No. 6,362,393)
Though pure-line varieties are the predominate form of barley grown for commercial barley production hybrid barley is also used. Hybrid barleys are produced with the help of cytoplasmic male sterility, nuclear genetic male sterility, or chemicals. Various combinations of these three male sterility systems have been used in the production of hybrid barley.
Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Allard, Principles of Plant Breeding, 1960; Simmonds, Principles of Crop Improvement, 1979).
Promising advanced breeding lines are thoroughly tested and compared to appropriate standards in environments representative of the commercial target area(s). The best lines are candidates for new commercial varieties; those still deficient in a few traits may be used as parents to produce new populations for further selection.
A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior genotype is to observe its performance relative to other experimental genotypes and to a widely grown standard variety. Generally a single observation is inconclusive, so replicated observations are required to provide a better estimate of its genetic worth.
A breeder uses various methods to help determine which plants should be selected from the segregating populations and ultimately which lines will be used for commercialization. In addition to the knowledge of the germplasm and other skills the breeder uses, a part of the selection process is dependent on experimental design coupled with the use of statistical analysis. Experimental design and statistical analysis are used to help determine which plants, which family of plants, and finally which lines are significantly better or different for one or more traits of interest. Experimental design methods are used to control error so that differences between two lines can be more accurately determined. Statistical analysis includes the calculation of mean values, determination of the statistical significance of the sources of variation, and the calculation of the appropriate variance components. Five and one percent significance levels are customarily used to determine whether a difference that occurs for a given trait is real or due to the environment or experimental error.
Plant breeding is the genetic manipulation of plants. The goal of barley breeding is to develop new, unique and superior barley varieties. In practical application of a barley breeding program, the breeder initially selects and crosses two or more parental lines, followed by repeated selfing and selection, producing many new genetic-combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop exactly the same line.
Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under unique and different geographical, climatic and soil conditions, and further selections are then made during and at the end of the growing season.
Proper testing should detect major faults and establish the level of superiority or improvement over current varieties. In addition to showing superior performance, there must be a demand for a new variety. The new variety must be compatible with industry standards, or must create a new market. The introduction of a new variety may incur additional costs to the seed producer, the grower, processor and consumer, for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new variety should take into consideration research and development costs as well as technical superiority of the final variety. It must also be feasible to produce seed easily and economically.
These processes, which lead to the final step of marketing and distribution, can take from six to twelve years from the time the first cross is made. Therefore, development of new varieties is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.
Barley (Hordeum vulgare L.), is an important and valuable field crop. Thus, a continuing goal of barley breeders is to develop stable, high yielding barley varieties that are agronomically sound and have good grain quality for its intended use. To accomplish this goal, the barley breeder must select and develop barley plants that have the traits that result in superior varieties.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.